I actually like Feitan's ability of Pain packer. To me that ability was awesome and very unique. Also to me it matches with him and for some reason I just like his whole fighting style. As for
other great abilities, I like Hisoka's bungee gum, very versatile and useful, Kurapica's power is just super powerful and great but its too powerful and feels kind of haxed. Like however Killua's
ability its interesting and like the electric concept, just a awesome way to use the ability.
I know the author had to make something like this but just punch would be boring. I hope he develops new abilities with Gon. Reinforcement would be Gon's strength since that is his characterization but I want him to use a weapon with reinforcement instead of just punch. I feel like Gon is a much weaker version of Uvogin. Though I like the emission style he incorporated in his fighting, it makes him more versatile but just a punch is still boring and not too interesting. Togashi already did that with Uvogin, I want Gon to develop a different powerful move with reinforcement and it has to be reinforcement since that is his specialty but a cooler move.
Honestly to me its the most creative manga there is. The whole fighting style is unique and lot more strategies are involved than any other manga except Death Note. The fighting is based lot on intellect and fighting at the right way. With Gon I just hope he develops new cool moves later on instead of just a punch. For now I like the punch because it matches him but I hope he develops something cooler and unique if not than I would be disappointed.